Learn more about our fine feathered friends during International Migratory Bird Day on Saturday, May 21. Walden Ponds, a cluster of former East Boulder quarries that have become an exemplary wildlife habitat, hosts the Boulder celebration from 9 a.m. to 2 p.m. with FREE activities for all ages. These include guided birdwalks, education stations along the flat and easy trails, an opportunity to see wild raptors, prizes, snacks and a bird piñata exhibition and judging. The parking area and trailhead are along 75th St. between Arapahoe and Valmont.